Casting press



y 2, 1940- K. F. WAGNER 2,206,211

CASTING mass Filed Feb. 10, 1937 2 sheets shee 1 frz aenfor War/1282M k6liywer I am r Jaw July 2, 1940.

K. F. WAGNER CASTING FRISS 2 Sheets-Sheet 2 Filed Feb. 10. 1937 Ill IIHHll HHIH Patented July 2, 1940 UNITED STATES 2,206,211 CASTING mmss KarlFriedrich Wagner, Friedrichshafen, Bodensee, Germany,

Application February 10, 1937, Serial No. 124,978 In Germany February13, 1936 Claims.

My invention relates to casting presses, i. e. to machines for castingmetal and more especially light metals under pressure. It has moreparticular reference to the pressure-casting of read- 5 ily oxidisablemetals such as magnesium or aluminum in such manner that the moltenmetal is not oxidized in contact with the air.

Hitherto, 'when feeding readily oxidisable metals of the kind here inview into casting presses with a pressure chamber located outside of thecrucible the metal has as a rule been ladled out by hand and has thusbeen exposed to oxidation. The protective matter covering the surface ofthe molten metal in the crucible had to be partly removed beforeentering the ladle in the metal, which was thus likely to becomeoxidized. Moreover the danger arose that together with the ladleobnoxious constituents of the protective cover might enter the pressurechamber together with the metal and that the metal and more especiallythe residual metal adhering to the ladle might come to burn during theoperation. All these drawbacks impaired the quality of the metal and thecastings made from it, which enclosed oxides and nitrites. Thesedrawbacks also necessitated expensive interruptions of the work and ledto considerable metal losses by continuous oxidation. The burning metalmay further endanger the health and life of the operators. i

The present invention relates to means whereby the casting of lightmetals including magnesium, aluminum, etc., and their alloys is greatlyfacilitated. The invention is applicable to casting presses with apressure chamber extending vertically, horizontally or obliquely. Inaccordance with this invention the molten metal is metered and conveyedfrom the melting pot into the pressure chamber located outside of themelting pot 1 L0 through closed spaces inaccessible to the outer air,which are arranged partly above and partly below the level of the moltenmetal and the melting pot. The quantity of molten metal to be pressed ismetered below the metal level and lifted, by means of a piston operatedfrom without, above the metal level until the molten metal enters thecasting channel. When a predetermined quan-v tity of metal has beendisplaced in this channel,

the metering piston will come to a standstill and 0 the feed pistonsliding in the channel now shifts the metal lying in front of it intothe pressure chamber adjoining the channel. Both the metering and thefeed piston are actuated from without the melting pot, preferably bypositively 5 operated cylinders and pistons acted upon by hydraulic orpneumatic pressure. Other mechanical means may however also be providedfor actuating the pistons. Since the pistons are required to operate atexactly predetermined periods, they are preferably actuated inconnection with the means actuating the casting press proper, however,in manually operated presses the two pistons might also be manuallyoperated.

The cylinder enclosing the metering piston is formed with a lateralopening through which fluid metal may enter the cylinder whenever themetering piston has been lowered to the extent of uncovering theopening. While the lower part of the metering cylinder is alwayssubmerged in the fluid metal, the charging channel formed integral withit is always arranged above the metal level. Preferably the cylinder andchannel are combined with a cover closing the melting pot. They may bemade in one or several pieces. V

The inner spaces thus formed above the metal level may be filled withinert gases or vapors or may be partly evacuated and part of the oxygenand nitrogen removed by evacuating the air therein." Incontradistinction to similar devices the joint faces between the meltingpot and the top covering same simply abut against each other without anypacking. Preferably the melting pot is formed with a marginal wallsurrounding its top and the space enclosed between the top and this wallmay be filled with material, such as carnallite, forming gases. If theinterior of the melting pot is evacuated, the ambient air enteringthrough the carnallite and the joints will carry carnallite vapors intothe melting pot, the

air in which takes up such vapors and consequently prevents oxidation ofthe metal. Since the carnallite 'or similar material does notpermanently develop vapors, the supply must be replenished from time totime, preferably by in- 40 serting in the space enclosed between the topof the melting pot and the cover some receptacles containing carnallite,which snugly fit this space. The melting pot and the header cover areheated uniformly so that also the carnallite is heated for evaporation.1 Particular importance is attached to that part of the charging channelwhich projects from the melting pot. above the metal level and connectsthe melting pot with the pressure chamber arranged in the casting press.This connection is so arranged that in spite of the close connectionbetween the melting pot and the casting press no obnoxious convection ofheat to the press takes place, although the charging channel is as Ifurther provide a protective sleeve surrounding the press stamp, whichpermanently prevents 15 the access of air to the space between thepressure chamber and the press stamp, except during the time when thediscard is expelled from the pressure chamber. The protective sleeve ispreferably arranged for displacement in parallel to 20. the press stampeither by hand or by means of a controlled or uncontrolled hydraulic orpneumatic power cylinder and piston. The interior, inaccessible to theouter air, of the protective sleeve may be connected with the interiorof the 25 melting pot by a pipe system, so that also the interior of thesleeve may be evacuated and filled with a gas poor in oxygen andnitrogen. The protective sleeve may however also be stationary and beformed with apertures, which may be 30.closed, for expelling the discardand it may be provided with means, independent of the melting ,pot, forevacuating air and introducing gas.

Obviously this invention does away with the injurious consequences ofthe modes of operation 35 hitherto used when casting light metals suchas magnesium or aluminum or its alloys incasting presses, since thefiuid metal is charged from the melting pot into the pressure chamber insuch manner, that the quantity of metal about to be '40 charged does notcome'in contact with the outer air and soiling of the metal and lossesby the formation of oxides and nitrites are avoided. The

invention further renders the charging of thepress more eflicient, sincethe quantity of metal 45 to be pressed is uniformly predetermined andfed to the pressure chamber, independently from the operator, by themechanically actuated metering device. In this manner the hithertounavoida ble wasting of metal by discards of different sizes 59 and bythe metal adhering to the ladle are avoided. Similar losses are hithertoencountered when removing the metal adheringto the ladle and returningit into the melting pot. This metal contains a high percentage ofimpurities and l 55 greatly impairs the qualities of the molten metal.

Apart from the light metals proper such as magnesium and aluminum, alsozinc and its alloys can be cast with advantage in the manner heredescribed.

In the drawings afllxed to this specification and forming part thereofan embodiment of my invention is illustrated? diagrammatically by way ofexample. t

In the drawings:

65 Fig. 1 isalongitudinal section and Fig. 2 a cross-section of themelting pot, the

charging device and pressing device, while Fig. 3 illustrates on alarger scale the means for adjusting the metering piston.

Referring to the drawings, is the melting oven and 2' is the melting potremovably mounted therein, while 3 is the metering cylinder, the .in-

take'opening 4 of which is arranged below the metallevel 5, whichispermanently maintained 7 at uniform level by well-known means (notshown). The intake opening 4 is preferably located near the center ofthe body of molten metal where the metal is known to be purer than inother parts. The charging channel 6 is preferably formed integral withthe metering cylinder. I is 5 the hood covering the metering cylinderand charging channel and closing up the melting pot,

at the same time preventing access of air to the metal. The heatinggases flowing around the melting pot rise above the hood 1 whereby themetal in the pot as also the parts arranged above the metal are heateduniformly. 8 is a cover cov ering the oven as a whole and serving tolead the heating gases in the desired direction and to reduce theradiation of heat. 9 is a piston reciproeating in this metering cylinder3, rods l0 and II connecting the piston with the power cylinder |2,

a cross piece I3 connecting the two rods, which are extended upwardly at|4, -|5 carry nuts l6, whereby the stroke of the piston l1 can beadjusted in accordance with the quantity of metal to be pressed.

In the channel 6, which is here formed with rectangular cross-section,the piston I8 is reciprocated by means of the level 20 and powercylinder IS. The piston l8 serves for forcing the metal lifted by themetering piston into the pressure chamber 2|, the end of the chargingchannel 6, which projects from the melting pot, forming a mouthpiecefitting exactly a notch in the wall of the pressure chamber 2|.

The wall of the melting pot is extended upwardly and this extension 23encloses with the part of the charging channel 6 and the hood I achamber 24, in which are mounted iron receptacles 25, containing bodiesof carnallite 26 or the like. The vapors developed by the heatedcarnallite are sucked, in consequence of the partial vacuum in theinterior 21 of the melting put, across the joints into the pot and serveto protect 40 the metal surface against oxidation. The am-- bientair assuch has no access to the metal surface in view of the very limitedpassage and since the air would have to first flow through theheatinggases in the oven chamber 28 and the chamber 24 filled withcarnallite. I may however also introduce into the melting pot inertgases or vapors under slight pressure above normal.

The press stamp 29 is surrounded by an axially displaceable sleevegoverned by a power. cylinder 33, to which it is connected by an arm 32.This sleeve serves for preventing air from entering the pressure chamber2| and. the charging channel as soon as the discard has been expelledfrom the chamber, the sleevebeing lowered, for this purpose, upon thepressure chamber, which may thus be evacuated'and filled with inertgases and may also communicate by a pipe system with the space 21 abovethe metal in the melting pot. I thereby succeed in preventing contact ofthe air with the molten metal with ensuing oxidation.

This device operates as follows:

The mold mounted in the casting press (not 2 shown), .the bottom end 34of which is shown in Fig. 1', being closed and in operative position,

the sleeve 3| is lowered by the piston 33 and airtightly seated on thepressure chamber 2|, while its interior is evacuated and filled with aninert gas flowing also into the charging channel 6. The meteringcylinder. 3 is filled with metal. The piston 9 is now lifted by thecylinder |2 until the nuts l6 meeting the stop 3] prevent the piston IIfrom rising further. In rising the piston 9 first covers the intakeopening I and on rising further lifts the metal into the chargingchannel 6. The quantity of metal above the piston 9 can be predeterminedexactly, by adjusting the nuts IE to form the casting with discard asdesired. Directly the ascent of the metering piston 9 has come to anend, the charging piston l8 will force the metal into the pressurechamber 2 I, where the metal is now pressed by the lowered press stamp29. While this is going on, the metering piston is lowered again,uncovering the intake opening land allowing the cylinder 3 to berefilled. The piston l8 also, returns into its initial position. During.the pressing it closes the mouth piece 22 in order to prevent anyresidual metal from entering the channel. As thepiston I8 is withdrawn,the protective sleeve 3| is also lifted, uncovering the aperture 35 ofthe pressure chamber, so that the discard can be expelled ina well-knownmanner, whereupon the sleeve 3! is lowered at once into operativeposition. On the mold being returned into casting position, the cycle ofmovements is gone through again.

I wish it to be understood that I do not desireto be limited to theexact details of construction I shown and described for obviousmodifications will occur to a person skilled in the art. I claim:

1. Apparatus for casting under pressure readily oxidizable metals,comprising in combination, a closed melting pot, a charging cylinderextending above said melting pot, a metering device permanentlyextending from said cylinder into said melting pot, a pressure chambercommunicating with said cylinder, a charging piston reciprocable in saidcylinder for conveying metal raised by said metering device from saidmelting pot towards said pressure chamber. andmeans for preventing airfrom entering said melting pot, said charging cylinder and said pressurechamber while the metal isso conveyed. g 2. The apparatus of claim 1 incombination with a press stamp above and arrangedto be lowered into saidpressure chamber and'a sleeve surrounding said press stamp and adaptedto be lowered. onto said chamber to temporarily prevent air fromentering said chamber and-the charging cylinder.

.3. The apparatus of claim l in combination 7 and communicating withsaid arranged to be heated together with said pot.

opening, a metering piston arranged for reciprocation'in the bottom partof said tube and past said opening, and means for reciprocating saidpiston,

with a gas developing chamber pro'videdabove melting potand 20 4.'Iheapparatusof claim lwherein the meteringdevicei comprises a tube,having an-intake 5. .The apparatus of claim 1 combination I with a.cooling jacketsurrounding the charging KARL FRIEDRICH WAGNER. so

cylinder. 7

